Home>Discussions>PLUMBING>What size copper should I use to replace Galvanized
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eboking01
What size copper should I use to replace Galvanized

Hello Everyone,
I'm looking to replace a 15' run of 2" leaky Galvanized Pipe water supply from my water meter. Actually, from the meter it looks like 3/4 inch copper for about 4' and then it joins into the Galvanized I'm looking to replace.

If I want to convert to copper, what size copper pipe should I use since I've only seen 1 1/2 copper pipe at the Depot?

Would the downsize affect my water pressure in the house?

After the 15' the Galvanized downsizes into 1/2 inch copper pipe.

Any help appreciated.

Blake
Re: What size copper should I use to replace Galvanized

What size is the pipe when it enters your house, does it up size from the 1/2" pipe again? Are there any other connections to the galvanized pipe before it reduces to the 1/2 inch pipe? What is the overall length of the water line from the meter to the house? By up sizing the pipe from the 3/4" line to 1-1/2" or 2" for 15 feet would relieve some friction loss in the pipe but not a lot, then reducing to 1/2" would remove the benefit of the up size. Replacing the 15 feet of galvanized pipe with 3/4" copper would not make a lot difference in your water pressure, but reducing the line to 1/2" has a big effect on the avaliable water volume, 1/2" pipe has less than half of the capacity of the 3/4" pipe. If the line upsizes again before entering your house I would replace the 1/2" part of the line too.

JLMCDANIEL
Re: What size copper should I use to replace Galvanized

Under the circumstances you describe, replace the 15' of galvanized pipe with 3/4" copper.
Jack

Blue RidgeParkway
Re: What size copper should I use to replace Galvanized

I can't imagine 3/4" copper to 2" galvanized then later reduced.

you cannot connect copper directly to galvanized steel you'd have fast corrosion if you did. you'd need a union.

if you really have a 3/4" supply then continue with 3/4" of the proper TYPE ( K, L, etc.) copper pipe. When you increase pipe size you reduce pressure when you reduce pipe size you incrase pressure. When you increase pipe size you increase flow, when you reduce pipe size you decrease flow.

You cannot connect different metals if you do one will quickly corrode and leak. There are special types of connectors to use when wanting to connect different metals. If your house electric is grounde to your water line you don't want to have these dielectric uniions before your connection bond to ground.

Your water supplier and the general public health probably requires that you have a permit and a licensed plumer for this for good reason, the general public health is at risk if you do not do it right.

Blake
Re: What size copper should I use to replace Galvanized

I agree that increasing or decreasing pipe size will change flow rates however it will not increase or decrease pressure.

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